Spring loaded pushbutton switch

ABSTRACT

A switch including opposed, spaced apart contacts, and a movable contact mounted in a carrier. The movable contact may comprise a transversely extending pin adapted to bridge the spaced apart contacts when the carrier is moved into one position. A spring is disposed within the carrier for normally biasing the movable contact in the direction of the spaced apart contacts whereby engagement of the movable contact with the spaced apart contacts will impart a force to the movable contact in opposition to the force of the resilient means. A pair of pins may be employed to provide redundancy, and pins may be located at opposite ends of the carrier with a separate set of spaced apart contacts being bridged by one or more separate pins.

[ 1 Jan. 16, 1973 United States Patent [191 Farrell PrimaryExaminer-Robert K. Schaefer Assistant Examiner-M. Ginsburg IAttorne.y-McDougall, Hersh & Scott 60606 [73] Assignee: Chicago SwitchInc.,

[57] ABSTRACT A switch including opposed, spaced apart contacts,

and a movable contact mounted in a carrier. The

movable contact may comprise a transversely extending pin adapted tobridge the spaced apart contacts when the carrier is moved into oneposition. A spring is disposed within the carrier for normally biasingthe [52] U.S. Cl. R [51] Int. 3/12 of Search R, A 159 B, 5 R movablecontact 1!] the dIrectIon 0f the spaced apart 200/5 A 5 B, 5 C, 5 D. 5 E5 EA, 5 EB 5 F, contacts whereby engagement of the movable contact 169P3 with the spaced apart contacts will impart a force to the movablecontact in opposition to the force of the resilient means. A pair ofpins may be employed to provide redundancy, and pins may be located atopposite ends of the carrier with a separate set of spaced apartcontacts being bridged by one or more separate pins.

2,363,854 Bierenfeld ......................200/l69 PB 1,744 626 1/1930Getchell ...........................200/159 R FOREIGN PATENTS 0RAPPLICATIONS 12 Claims 12 Figures 5/1968Germany...I....................,.200/159R PATENTEUJAH 16 I975 SHEET 2 BF2 FIG, 5 F1619 FIGJO FIG. 1 1

SPRING LOADED PUSIIBUTTON SWITCH This invention relates to an improvedswitch construction employing resilient means for engaging contacts inthe switch. The invention is particularly concerned with a switchconstruction having greatly improved operating characteristics,particularly from the standpoint of bounce" characteristics.

Many circuit applications require switches which require movement ofswitch contacts into engagement at high relative speeds. For example, anoperator may engage a push button which will move one set of contactsrapidly into engagement with another set of contacts and, of course, adegree of energy will be involved in this movement proportional to thespeed and force of application.

The energy must be dissipated in some fashion, and in many switches, thedissipation involves bounce of the contacts. For example, where amovable contact is driven against a stationary contact, the movablecontact will often bounce back or disengage momentarily because of thereaction force. This can create significant problems in sensitivecircuits since the momentary disengagement of the contacts will providea break which could lead to a false signal. For example, a signal couldbe transmitted upon initial engagement of the contacts, and then asecond signal transmitted subsequent to the bounce.

It is a general object of this invention to provide an improved switchconstruction which overcomes problems which particularly occur withswitches employed in sensitive electrical circuits.

It is a more particular object of this invention to provide a switchconstruction which is characterized by freedom from bounce to the extentthat no apparent effect on circuit operation will occur even in highlysensitive circuitry.

These and other objects of this invention will appear hereinafter, andfor purposes of illustration, but not of limitation, specificembodiments of the invention are shown in the accompanying drawings inwhich:

FIG. 1 is an elevational view of the switch construction of thisinvention, partly in section, and taken about the line I-l of FIG. 3;

FIG. 2 is an elevational view of the switch construction illustratingthe contact carrier in the depressed position;

FIG. 3 is a vertical sectional view of the switch construction takenabout the line 33 of FIG. 1;

FIG. 4 is an elevational view, partly in section, taken about the line4-4 of FIG. 3;

FIGS. 5, 6 and 7 are horizontal sectional views taken about the lines55, 6-6 and 77, respectively, of FIG. 1;

FIG. 8 is an exploded perspective view of the switch construction shownin FIG. 1;

FIG. 9 is an elevational view, partly cut away, illustrating a modifiedform ofthe invention;

FIG. 10 is an exploded elevational view of the switch construction shownin FIG. 9;

FIG. 11 is an enlarged plan view of the switch housing taken about theline 11-11 of FIG. 10; and,

FIG. 12 is a bottom plan view of the switch housing taken about the lineI2-l2 of FIG. 10.

This invention generally concerns a switch construction which includesopposed spaced apart contacts mounted within a housing. A movablecontact is located on a carrier, and means are provided for displacingthe carrier within the housing to thereby move the movable contact intoand out of bridging relation with the spaced apart contacts. The movablecontact is held within the carrier by means of a spring or otherresilient means which biases the movable contact in the direction of thespaced apart contacts.

In the switch operation, the carrier moves the movable contact towardand away from the spaced apart contacts. When engaging the spaced apartcontacts, the resilient means mounted within the carrier immediatelyresists any tendency of the movable contact to bounce away from thespaced apart contacts. The design of the switch construction issuch-that this operation can be achieved in a highly efficient mannerfrom a part cost and assembly standpoint whereby the switches can beeconomically produced for use in large numbers, particularly in circuitswhich benefit from the elimination of apparent bounce.

The embodiment of the invention shown in FIGS. 1 through 8 comprises aswitch I0 including a housing 12. The housing includes a bottom recess14, and a plurality of terminals 16 are exposed within this recesswhereby the switch can be included in a circuit. The terminal 16 may beof the type requiring attachment of leads or may be suitable forinsertion in a printed circuit board.

In the embodiment shown, the terminals 16 comprise extensions of sheetmembers which are located within the housing 12. A first sheet member 18defines an exposed upper edge 20 and a second sheet member 22 defines anexposed edge 24 located in the same plane as the edge 20. A third sheetmember 26 defines an exposed lower edge 28. A fourth exposed edge 32 isdefined by the sheet member 22. Thus, as best shown in FIG. 8, the sheetmember 22 defines a pair of terminals 16 while the sheet members 18 and26 are separate from each other and define individual terminals. As bestshown in FIGS. 5, 6 and 7, these sheet members are located withinpassages defined by the interior walls of the housing whereby therespective sheet members are insulated from each other. T-shapedportions 34 and 36 form passages at the bottom of the construction forconfining the lower ends of the four members. The four rails 38 maintainthe separation throughout the length of the housing.

The rails 38 also define grooves 40 which serve as guides for the sideedges 42 of plate 44. The plate 44 includes an upper portion 46extending outwardly of the housing 12, and a button 48 is secured onthis extension. As will appear, the combination of the plate 44 andbutton 48 serve as a plunger mechanism for operating the switch.

The plate 44 defines a central opening 50 (FIG. 8) for receiving acarrier 52. This carrier defines a lower groove 54 adapted to engage thelower edge 56 of the opening 50. The combination of the groove 54 andupper tabs 58 provide a means for locating the carrier 52 on the plungerduring the assembly operation.

The carrier defines a central bore 60 and slots 62 defined in its sidewalls. Contact pins 64 are inserted within the slots with the spring 66being disposed between the contact pins. This arrangement resilientlyholds the contact pins against the ends of the slots 62.

The pins 64 extend outwardly beyond the sides of the carrier wherebythese pins are adapted to bridge the contacts provided by theaforementioned sheet members. In the example illustrated, the upper setof pins forms a bridge between the edges 28 and 32 while the lower setforms a bridge between the edges 20 and 24, the bridging conditiondepending upon the position of the switch.

The switch position is controlled by means of a spring 68 which isseated against the closed bottom 70 of the housing 12. The upper end ofthe spring is positioned around central arm 72 defined by the plate 44.With this arrangement, the switch is normally held in the position shownin FIGS. 1 and 3. Upon depression of the plunger, the position shown inFIG. 2 will be achieved.

In the operation of the switch construction, the depression of theplunger will result in breaking of the bridging contact between theupper set of pins 64 and the contact edges 28 and 32. Continueddepression will then serve to make bridging contact between the lowerset of pins 64 and the contact edges 20 and 24.

This break before make" arrangement is not required, however, since thestructure can be easily designed to provide making of the lower set ofcontacts before breaking of the upper set, for example, by locating thesets of contact edges closer together, or by increasing the size of thecarrier to provide longer slots. The switch can also be designed toprovide a normally open condition wherein the carrier will hold the pinsat some intermediate location. Similarly, an all contacts closedcondition can be achieved without difficulty, and in this case,depression of the plunger will break one side while retracting of theplunger will break the other side.

The use of sheet members of the type shown which provide the contactedges also leads to a great deal of the versatility. For example, thesheet member 22 could be divided to thereby change the switchingcharacteristics. It is also possible to design sheet members which areseparated so that they will be engaged by only one pin whereby theredundant features which characterize the illustrated switch will beeliminated. It is preferred, however, to provide the redundantarrangement in order to decrease the possibility of losing contactbecause of contamination.

Irrespective of the particular design employed, the low bouncecharacteristics of the switch are achieved. This is accomplished due tothe fact that the spring 66 mounted within the carrier 52 willimmediately resist any tendency of the pins 64 to disengage from thecontact edges. In this connection, the redundancy is also of valuesince, even if there is a slight bounce in both pins, chances are thebounces will not be in phase, and, therefore, contact will not beinterrupted. It will be appreciated that in referring to the eliminationof bounce, apparent bounce only is being considered. Thus, problems invery sensitive circuits are eliminated as long as the circuitinterruption due to bounce is so short that even sensitive circuits willnot detect the interruption. The switch structure described is highlyeffective for eliminating any detectable or apparent bounce.

FIGS. 9 through 12 illustrate one alternative design possible inaccordance with the teachings of this invention. In this embodiment, theswitch includes a housing 82 and a cover 84. This cover includesdownwardly extending tabs 86 adapted to snap over shoulders defined bythe housing 82. A central opening for receiving the upper end 88 ofplunger. 90 is defined by this cover.

The housing 82 defines a closed bottom 92, and spring 94 seats on thisbottom. A central arm 96 defined by the plunger 90 receives the upperend of this spring whereby the plunger is normally maintained in theupper position and is adapted to be depressed through engagement of theextension 88.

A carrier 98 'of the type previously described is located within acentral opening defined by the plunger. A compression spring 100 locatedwithin the body of the carrier presses downwardly on the contact pins102. These pins are located within slots 104 and extend outwardly oneither side of the carrier in the manner previously described.

A pair of contacts 106 are located within the housing 82. These contactsdefine edges 108 which are located in spaced relationship and which areadapted to be bridged by the pins 102. The terminals 110 of the switchcomprise integral extensions of the sheet members 106. As best shown inFIG. 9, shoulders 112 are defined by the interior walls of thehousing82, and these shoulders engage the lower edge portions 114 of thecontacts 106 for purposes of accurately locating the contacts within thehousing.

In the operation of the switch 80, the plunger 90 is normally in theraised position whereby the pins 102 are out of contact with thestationary contact'edges 108. Upon depression of the plunger, thepins-102 move into engagement with these edges. In the absence oflatching means which could be employed for holding the plunger in adepressed condition, release of the plunger will result in breaking ofthe contacts.

The structure shown in FIGS. 9 through 12 is a relatively simple switchdesign which includes the low bounce characteristics but which can bemanufactured at a very low cost. This is a highly important factor inthat switches of this type must often be employed in very large numberswhereby any savings achieved in an individual switch will be multipliedmany times.

It will be understood that various changes and modifications may be madein the above described construction which provide the characteristics ofthis construction without departing from the spirit thereof particularlyas defined in the following claims.

That which is claimed is:

1. In a switch construction comprising opposed, spaced apart contacts, amovable contact, a carrier for said movable contact, said carrier beingadapted to be located in a first position whereat said movable contactis spaced from said spaced apart contacts and in a second positionwhereat said movable contact bridges said spaced apart contacts, meansfor displacing said carrier to move the carrier between said first andsecond positions, resilient means associated with said carrier andbearing against said movable contact to bias said movable contact towardsaid spaced apart contacts, and a housing receiving said carrier, andsaid movable and spaced apart contacts, the improvement wherein saidmovable contact comprises at least one pin extending transverselyrelative to said carrier with the ends of the pin being exposedoutwardly of the carrier for engagement with said spaced apart contacts,and wherein said spaced apart contacts comprise thin sheet membershaving edges extending along a line perpendicular to the axis of saidpin, the ends of said pin contacting said edges, and passages defined bythe interior walls of said housing for receiving said sheet members andholding the sheet members spaced apart.

2. A construction in accordance with claim 1 including terminalsextending outwardly for including the construction in a circuit, saidterminals comprising an integral portion of said sheet members.

3. A construction in accordance with claim 2 including a second set ofspaced apart contacts positioned on the opposite side of said carrierrelative to said first mentioned spaced apart contacts.

4. A construction in accordance with claim 3 including a second movablecontact mounted in said carrier in spaced relationship with said firstmovable contact, said resilient means bearing against said secondmovable contact to thereby bias said second movable contact toward saidsecond set of spaced apart contacts.

5. A construction in accordance with claim 3 including a second set ofterminals extending outwardly for including said second spaced apartcontacts in an electrical circuit, said second spaced apart contactscomprising sheet members defining exposed edges for engagement with amovable contact, and said terminals comprising integral portions of saidsheet members.

6. A construction in accordance with claim 1 wherein said means fordisplacing said carrier comprising a plate member movable within saidhousing, said plate member defining an opening receiving said carrierand securing the carrier to the plate member.

7. A construction in accordance with claim 6 wherein said housingdefines a closed bottom and a compression spring extending between saidbottom and said plate member for normally holding said carrier in one ofsaid positions.

8. A construction in accordance with claim 7 including grooved areasdefined in the walls of said housing, the edges of said plate memberbeing received in said grooved areas for guiding said plate member.

9. A construction in accordance with claim 6 wherein said plate memberincludes an extension disposed outwardly of said housing, and meansengaging said extension for imparting movement to said plate member.

10. A switch construction comprising first and second pairs of opposed,spaced apart contacts, movable contacts, a carrier for said movablecontacts, means whereby said carrier is adapted to be located in atleast first and second positions, said movable contacts comprising pinsand resilient means within said carrier for holding said pins in spacedrelationship with each other, at least one of said pins bridging thefirst pair of spaced contacts in the first position of said carrier andat least one other pin bridging the second pair of spaced contacts inthe second position of said carrier, said resilient means biasing therespective bridging pins against the bridged spaced contacts wherebyengagement of a pin with spaced apart contacts imparts a force to saidpin in opposition to the force of said resilient means.

. A construction in accordance with claim 10 wherein said resilientmeans comprises a compression spring mounted within said carrier.

12. A construction in accordance with claim 10 wherein each of saidmovable contacts comprises a pair of pins held apart by said resilientmeans to provide redundant contact with said spaced apart contacts.

1. In a switch construction comprising opposed, spaced apart contacts, amovable contact, a carrier for said movable contact, said carrier beingadapted to be located in a first position whereat said movable contactis spaced from said spaced apart contacts and in a second positionwhereat said movable contact bridges said spaced apart contacts, meansfor displacing said carrier to move the carrier between said first andsecond positions, resilient means associated with said carrier andbearing against said movable contact to bias said movable contact towardsaid spaced apart contacts, and a housing receiving said carrier, andsaid movable and spaced apart contacts, the improvement wherein saidmovable contact comprises at least one pin extending transverselyrelative to said carrier with the ends of the pin being exposedoutwardly of the carrier for engagement with said spaced apart contacts,and wherein said spaced apart contacts comprise thin sheet membershaving edges extending along a line perpendicular to the axis of saidpin, the ends of said pin contacting said edges, and passages defined bythe interior walls of said housing for receiving said sheet members andholding the sheet members spaced apart.
 2. A construction in accordancewith claim 1 including terminals extending outwardly for including theconstruction in a circuit, said terminals comprising an integral portionof said sheet members.
 3. A construction in accordance with claim 2including a second set of spaced apart contacts positioned on theopposite side of said carrier relative to said first mentioned spacedapart contacts.
 4. A construction in accordance with claim 3 including asecond movable contact mounted in said carrier in spaced relationshipwith said first movable contact, said resilient means bearing againstsaid second movable contact to thereby bias said second movable contacttoward said second set of spaced apart contacts.
 5. A construction inaccordance with claim 3 including a second set of terminals extendingoutwardly for including said second spaced apart contacts in anelectrical circuit, said second spaced apart contacts comprising sheetmembers defining exposed edges for engagement with a movable contact,and said terminals comprising integral portions of said sheet members.6. A construction in accordance with claim 1 wherein sAid means fordisplacing said carrier comprising a plate member movable within saidhousing, said plate member defining an opening receiving said carrierand securing the carrier to the plate member.
 7. A construction inaccordance with claim 6 wherein said housing defines a closed bottom anda compression spring extending between said bottom and said plate memberfor normally holding said carrier in one of said positions.
 8. Aconstruction in accordance with claim 7 including grooved areas definedin the walls of said housing, the edges of said plate member beingreceived in said grooved areas for guiding said plate member.
 9. Aconstruction in accordance with claim 6 wherein said plate memberincludes an extension disposed outwardly of said housing, and meansengaging said extension for imparting movement to said plate member. 10.A switch construction comprising first and second pairs of opposed,spaced apart contacts, movable contacts, a carrier for said movablecontacts, means whereby said carrier is adapted to be located in atleast first and second positions, said movable contacts comprising pinsand resilient means within said carrier for holding said pins in spacedrelationship with each other, at least one of said pins bridging thefirst pair of spaced contacts in the first position of said carrier andat least one other pin bridging the second pair of spaced contacts inthe second position of said carrier, said resilient means biasing therespective bridging pins against the bridged spaced contacts wherebyengagement of a pin with spaced apart contacts imparts a force to saidpin in opposition to the force of said resilient means.
 11. Aconstruction in accordance with claim 10 wherein said resilient meanscomprises a compression spring mounted within said carrier.
 12. Aconstruction in accordance with claim 10 wherein each of said movablecontacts comprises a pair of pins held apart by said resilient means toprovide redundant contact with said spaced apart contacts.